State diagram modeling environments provide tools that allow users to build and simulate models including graphical representations of state machines. These models are useful in a number of contexts, such as when a modeled entity is responsive to one or more events. Conventional state diagram modeling environments suffer from a number of limitations. For example, conventional state diagrams can grow large and unwieldy, and thus may become difficult to edit and/or debug. Further, it may be difficult to reuse components from a first part of a state diagram model into a second part of a state diagram model (or in a different state diagram model).